There is a scene in Pixar's hit film Inside Out 2 as teenager Riley, the human protagonist of the From the inside out World, senses that one of her 13-year-old friends isn't telling her everything. The audience zooms into Riley's mind as her emotions try to figure it all out. The disgust expressed by Mindy Kaling is added to this. She pulls up a screen and begins examining Riley's friend's furrowed brow. “Improve,” barks disgust as the gaze penetrates the tell-tale corrugated muscle that controls our eyebrows.

This scene, said Dacher Keltner, a psychology professor at UC Berkeley, is very rooted in science. He would know: He worked on it with Pixar as a scientific advisor From the inside out films for over a decade.

“I feel like they're making a joke about what I've been talking to them about for the last 14 years,” he said in this episode of UC Berkeley's “Academic Review” video series. “I gave them tutorials on facial muscles; There are 30 muscles under the skin that connect in different ways to express emotions.”

Keltner spent much of his early career cataloging and analyzing how emotions, particularly embarrassment, play out on our faces. That the film contains an inside joke about this kind of real-world research is perhaps unsurprising. From the inside out And Inside Out 2 Ultimately, it's about the emotions that drive how we feel and behave, and there are many allusions to the advances in understanding we have gained in the areas of mental health, emotions and mindfulness.

In this video, Keltner, who has been teaching students about human emotions at UC Berkeley for over 25 years and is co-director of the university's Greater Good Science Center, reveals the real science behind the Disgust microexpression scene and the new characters in the films.

Maybe we have him to thank for all the new emotional characters that are added to the original five Inside Out 2: Fear, envy, boredom and embarrassment. When Keltner first spoke to Pete Docter, the director of From the inside outHe explained that there are 25 emotions that scientists like him have cataloged. Docter, in turn, explained that it was impossible to have 25 main characters in a film, but the number now stands at nine as Riley's emotions increase in her teenage years.

Watch the video to learn more about how scientific research led Pixar to cast Joy as the emotional protagonist of the first film, and why fear is the driving force and emotional force Inside Out 2 Now that Riley is a teenager.
Click here to watch a previous Academic Review video on the origins and stories behind national anthems, analyzing deepfakes, and linguistics by Kamala Harris.